| 摘要 |
936,953. Locating conductive bodies. CROSS CO. Dec. 16, 1959 [Dec. 17, 1958], No. 42743/59 Class 37. [Also in Groups XXII and XL (c)] A machine tool (such as a drilling-machine) having a cutting tool supported by a movable head has sensing means, operative when the tip of the tool is about to engage a workpiece, for detecting when the length of the cutting tool is improper (broken, or too short or too long) comprising sensing means disposed adjacent the path of travel of the cutting tool. A head 12, Fig. 2, carrying drills 16, 18, is slidable on a base 10 towards and away from a workpiece 26. Inductance coils 28, 30, are supported by a member 32 fixed in position relative to the base 10 apertures 34, 36, in the member 32 allow the drills to pass through the coils to the workpiece. The coils may be embedded in the walls of member 32 or may be wound on bobbins mounted as inserts therein. The bobbins may serve as bushing elements to guide the drills. A bracket 40 is secured to the drilling head and supports ferrous rods 44, 46, these are adapted to pass through inductance coils 50, 52, secured to a member 48 fixed with respect to the base 10. The rods are arranged so that at the point of entry of a drill, e.g. 18, into the corresponding coil 30 the rod 46 is just leaving its coil 52. Electrical sensing and control means. Control means is provided for sensing the conjoint inductance of inductance coils 28 and 50 and similarly for coils 52 and 30, so adjusted that a circuit is set in oscillation if a drill is adjusted too short or too long or is broken. The control means shown in Fig. 6 comprises an oscillating circuit in which the two coils 28 and 50 form a part. One rod 44 only is shown connected to the head 12. The coils are centre-tapped and connected in parallel. A vacuum tube VIA serves as energy supply means with vacuum tubes V1B and V2A as amplifying means. Vacuum tube V2B controls the output relay CR1 which in turn controls relay CR2 to perform the output function. Triode V1A is connected as a Hartley type of feed-back oscillator. The circuit is arranged so that tube V1A is normally quiescent, the circuit breaking into oscillation only if at some instant no portion of rod 44 is disposed within coil 50 at the same instant that no portion of tool 16 is disposed within coil 28. At this instant relay CR2 in releasing closes its No. 2 contacts to energize lamp L1 to indicate a trouble condition and opens its No. 3 contacts to shut down the machine. Two other circuit arrangements are described (Figs. 12 and 14, not shown), in these arrangements limit switches and dogs are employed selectively to energize the sensing and/or control means, in lieu of the position detecting coil and rod arrangement. Specification 753,916 is referred to. |
